The mission of the Training Program in Environmental Epidemiology is to prepare a cadre of outstanding researchers in environmental epidemiology through a program of rigorous training and research methodology. This program is currently in its 29th year and is the established cornerstone of support for students working in area of environmental epidemiology at the Harvard School of Public Health. To date the investigators have graduated 177 professionals who conduct research, teach, and consult in environmental epidemiology and related disciplines, with 28 supported since the last competitive submission. The track in environmental molecular epidemiology, which was developed to provide trainees with comprehensive exposure to the application of molecular genetics techniques to environmental epidemiologic research, is now established and flourishing with trainees and new faculty. Training for both of these tracks is offered at the pre- and postdoctoral levels. Pre-doctoral students in the environmental track take courses in epidemiology, exposure analysis, exposure biology, biostatistics, occupational health, toxicology, and biomarkers. Additional research credits are obtained on the methodology of epidemiologic research through tutorials on current problems in epidemiology, and from the completion of a doctoral thesis of substance. In addition to course offerings, the track in environmental molecular epidemiology offers trainees additional courses in molecular biology and genetics, and the opportunity to select from four laboratories dedicated to research in molecular epidemiology with emphasis upon gene- environment interactions. The pre-doctoral training period usually lasts between 3 to 5 years, but varies depending on the students' preparation. The first 2 years are devoted primarily to course work. Most didactic teaching is shared by the Departments of Epidemiology and Environmental Health at the School of Public Health, but also includes a large host of affiliates working within the Harvard Medical Area. Postdoctoral trainees are exposed to a wide variety of interdisciplinary and integrated intellectual offerings, including didactic instruction, seminars, professional colloquia, meetings, and academic collaboration. Significant research usually begins for the postdoctoral fellow in his/her second year and varies in duration depending on the scope of work. The program has been updated according to the NIEHS NOT-ES-06-007, with programmatic focus on priority areas and exposures. This program will continue a long history of excellence in training successful researchers in the field of environmental epidemiology at Harvard University. Relevance: The Training Program in Environmental Epidemiology produces a continuing group of outstanding researchers who assess the role of environmental exposures in disease risk. This education involves state-of-the-art training in quantitative, biological and physical sciences. These young scientists go on to become leaders in the field, and work to identify, to prevent and control environmental risks.